Citizenship is an attitude, a state of mind, an emotional conviction that the whole is greater than the part...and that the part should be humbly proud to sacrifice itself that the whole may live.
Military sci-fi usually draws a pretty specific type of reader. People who are interested in equipment specs, detailed explanations of how warp drives and spaceships work. Starship Troopers has enough military flair to satisfy these readers, but there's also the traditional Robert A. Heinlein sense of morals woven into the characters. We repeatedly hear about the importance of individuals contributing to their societal good, taken to it's futuristic extreme as only veterans are allowed the title of "citizen".
I found the characters compelling and the story believable. More than reading a tale of science fiction, it felt more like I was gaining insight into a soldier's brain that just happened to be in the future. There are a number of chilling elements such as the flippant way the cap troopers drop bombs and fire onto their enemies. One of the more interesting literary aspects is how much more interesting the character scenes are than any of the actual battles depicted.
A couple elements had me shaking my head, but overall this was a very tight-knit piece of commentary disguised as military sci-fi. A subversive tale similar to Stranger In A Strange Land, on the short list for any sci-fi fan.